Composite ceramics and ceramic particles and method for producing ceramic particles and bulk ceramic particles

ABSTRACT

Methods for producing Polymer Derived Ceramic (PDCs) particles and bulk ceramic components and compositions from partially cured gelatinous polymer ceramic precursors and unique bulk composite PDC ceramics and unique PDC ceramic particles in size and composition. Methods of making fully dense PDCs over approximately 2 μm to approximately 300 mm in diameter for applications such as but not limited to proppants, hybrid ball bearings, catalysts, and the like. Methods can include emulsion processes or spray processes to produce PDCs. The ceramic particles and compositions can be shaped and chemically and materially augmented with enhancement particles in the liquid resin or gelatinous polymeric state before being pyrolyzed into ceramic components. Nano-sized ceramic particles are formed from the green body produced by methods for making bulk, dense composite ceramics. The resulting ceramic components have a very smooth surface and are fully dense, not porous as ceramic components from the sol-gel process.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.14/858,096, filed Sep. 18, 2015, now U.S. Pat. No. 9,764,987, whichclaims the benefit of priority to U.S. Provisional Patent ApplicationSer. No. 62/053,479 filed Sep. 22, 2014, and application Ser. No.14/858,096, filed Sep. 18, 2015, now U.S. Pat. No. 9,764,987 is aContinuation In Part of U.S. patent application Ser. No. 14/598,658filed Jan. 16, 2014, now U.S. Pat. No. 9,434,653 which is a Divisionalof U.S. patent application Ser. No. 13/775,594 filed Feb. 25, 2013, nowU.S. Pat. No. 8,961,840, which claims the benefit of priority to U.S.Provisional Application Ser. No. 61/606,007 filed Mar. 2, 2012. Theentire disclosure of each application is incorporated herein by specificreference thereto.

FIELD OF INVENTION

This invention relates to ceramics and ceramic particles andcompositions, and in particular to composite Polymer Derived Ceramics(PDCs) and polymer derived ceramic (PDC) particles and compositions, andmethods for producing ceramic PDC particles fully dense sizes of over300 μm.

BACKGROUND AND PRIOR ART

Polymer derived ceramics (PDCS) have been developed over the last 30years and have been processed into bulk or macroporous components. PDCsare becoming increasingly popular in applications involvinghigh-temperature resistant materials, hard materials, chemicalengineering applications or functional materials in electricalengineering as well as in micro/nanoelectronics. See Colombo et al.,Polymer-Derived Ceramics: 40 Years of Research and Innovation inAdvanced Ceramics, Journal of the American Ceramic Society, Vol. 93, No.7, 2010, pages 1805-1837.

Sol-gel and Flame pyrolysis are typically used to make typical ceramicparticles, and using an emulsion process has been known to make smallsize particles.

In a paper by Congwang Ye et al (“Ceramic microparticles and capsulesvia microfluidic processing of a pre-ceramic polymer”) Journal of theRoyal Society Interface 6 Aug. 2010 vol 7 Supp 4 S461-473, Ye describesa laboratory emulsion process which produces oxycarbide particles in the30-180 μm range. The problems with this laboratory technology includenon-manufacturability due to tedious washing schemes and the use ofpartially cross-linked resins in the emulsion phase which will produceinconsistent products and poorer quality particles which will not beable to be produced above the 200 micron size range.

Larger beads, particles, balls made with porosity have been made but notany that are fully dense in the size ranges over approximately 300 μm.

Fully dense particles/beads/balls do not have porosity or the flaws ofporous particles which should allow for better surface characteristicsin terms of roughness and reduction of crack propagation.

The current developments of PDCs does not enable making PDCs to be fullydense in sizes over approximately 200 μm to approximately 300 μm.

Thus, the need exists for producing PDC particles in high volumemanufacturing as well as producing unique particles in terms of size(large PDC particles) and unique in terms of composition.

SUMMARY OF THE INVENTION

A primary objective of the present invention is to provide large PolymerDerived Ceramic (PDC) particles and compositions from approximately 200μm to approximately 100 mm in diameter and methods of making theparticles and compositions having a new and novel composition from avariety of polymer derived ceramic resins using emulsion processing.

A secondary objective of the present invention is to provide largePolymer Derived Ceramic (PDC) particles and compositions fromapproximately 200 μm to approximately 100 mm in diameter and methods ofmaking these particles and compositions having a new and novelcomposition from various polymer derived ceramic resins, which are notproduced with flame pyrolysis or typical sol-gel processes.

A third objective of the present invention is to provide Polymer DerivedCeramic (PDC) particles and compositions from approximately 10 nm toapproximately 100 mm in diameter having a new and novel composition froma variety of polymer derived ceramic resins using emulsion processing.

A fourth objective of the present invention is to provide PolymerDerived Ceramic (PDC) particles and compositions from approximately 10nm to approximately 100 mm in diameter having a new and novelcomposition from a variety of polymer derived ceramic resins which arenot produced with flame pyrolysis or typical sol-gel processes.

A fifth objective of the present invention is to provide Polymer DerivedCeramics (PDCs) and methods of forming PDCs having a new and novelcomposition from an emulsion process formed into ball shapes having asphericity which is less costly than current ball grinding processes.

A sixth objective of the present invention is to provide Polymer DerivedCeramics (PDCs) and methods of forming PDCs from an emulsion processhaving very small particle sizes of approximately 0.001 to approximately10 micron with a very tight distribution. This process will involveusing the emulsion process with droplet injection or mechanical shaping(grinding) of the cured polymer bead. (The cryo-milling of a green bodyis one embodiment of mechanical shaping.)

Preferably, a polymer derived ceramic (PDC) particle of the presentinvention is a fully dense PDC particle formed from a gelatinous polymerceramic precursor material having a plurality of enhancement particlesattached to and incorporated in the structure of the gelatinous polymerceramic precursor material with an overall particle size ofapproximately 0.1 mm to approximately 300 mm in diameter.

Preferably, the polymer derived ceramic (PDC) particle of the presentinvention has a plurality of enhancement particles attached to thestructure of the gelatinous polymer ceramic precursor material includingat least one coating of a functional material coated on the surface ofthe gelatinous precursor material and a second coating of a secondfunctional material coated on the surface of a fully cured gelatinouspolymer ceramic precursor material that has one coating of a functionalmaterial, thereby forming an enhanced multilayered ceramic particle.

It is also preferred that the polymer derived ceramic (PDC) particle ofthe present invention have a plurality of enhancement particles selectedfrom functional materials that include a metallic powder, a ceramicpowder, graphite powder, graphene powder, diamond powder, carbidepowder, silicide powder, nitride powder, oxide powder, carbon nanotubesand mixtures thereof.

Preferably, a polymer derived ceramic (PDC) particle of the presentinvention has a density range of approximately 1.7 to approximately 3.4g/cc.

Further, it is preferred that the polymer derived ceramic (PDC) particleof the present invention is used for a proppant in fracking oil and gaswell, or for a ball bearing. It is also preferred that the polymerderived ceramic (PDC) particle material is derived from at least one ofthe following binary systems: a BN PDC System, a SiC PDC System; ternarysystems: a SiOC PDC System, a SiCN PDC System; and the followingquaternary systems: a Si—Ti—C—O PDC System, a Si—Al—C—O PDC System, aSi—B—C—N PDC System and a Si—Al—O—N PDC System.

A preferred method of making a plurality of polymer derived ceramic(PDC) particles in an emulsion process includes providing a liquidpre-catalyzed polymeric ceramic precursor resin, introducing theprecursor resin to a continuous phase liquid emulsion, exposing thecontinuous phase liquid emulsion containing the precursor resin to anenergy source, curing the precursor resin to form a partially curedgelatinous polymer, mixing a plurality of enhancement particles with thecontinuous phase liquid emulsion containing the partially curedgelatinous polymer, coating the partially cured gelatinous polymer withenhancement particles, separating the coated partially cured gelatinouspolymer from the continuous phase liquid emulsion; and pyrolizing thecoated partially cured gelatinous polymer to produce a plurality ofenhanced polymer derived ceramic (PDC) particles.

It is also preferred to mix the liquid pre-catalyzed polymeric ceramicprecursor resin of the present invention with a plurality of enhancementparticles before introducing the precursor resin to the continuous phaseliquid emulsion.

In the emulsion process herein, it is preferred to repeat enhancementcoating steps multiple times to create multiple layers of enhancementparticles on a coated partially cured gelatinous polymer forming anonion-like, layered, multi-functional composite that is fully cured andthen pyrolyzed to produce a unique, novel enhanced polymer derivedceramic (PDC) particle.

Another preferred method of making a plurality of polymer derivedceramic (PDC) particles uses a spray process that includes providing acuring chamber with a top opening, side walls, a bottom opening and anenergy source, introducing a liquid pre-catalyzed polymeric ceramicprecursor resin into the top opening of the chamber, exposing theprecursor resin to the energy source in the chamber, curing theprecursor resin to form a partially cured gelatinous polymer, spraying aplurality of enhancement particles into the chamber containing thepartially cured gelatinous polymer, coating the partially curedgelatinous polymer with the enhancement particles, collecting the coatedpartially cured gelatinous polymer from the bottom opening of thechamber; and pyrolizing the coated partially cured gelatinous polymer toproduce a plurality of enhanced polymer derived ceramic (PDC) particles.

It is also preferred to mix a liquid pre-catalyzed polymeric ceramicprecursor resin with a plurality of enhancement particles before theprecursor resin is introduced into the top opening of the curingchamber.

The preferred enhancement particles used to make the polymer derivedceramic (PDC) particles herein are selected functional materialsincluding, but not limited to, a metallic powder, a ceramic powder,graphite powder, graphene powder, diamond powder, carbide powder,silicide powder, nitride powder, oxide powder, carbon nanotubes andmixtures thereof.

Emulsions are mixtures of two or more liquids that are separated byelectrostatic forces and surface tension. The micelles are created by asurfactant lowering the interfacial tension. The micelles are veryspherical and have a very smooth surface. The micelles are non-porous.

Further objects and advantages of this invention will be apparent fromthe following detailed description of the presently preferredembodiments which are illustrated schematically in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a process for making polymer derived ceramic (PDC)particles using an emulsion process.

FIG. 2 shows a process for making polymer derived ceramic (PDC)particles using a spray process.

FIG. 3 shows an example of the quality and sphericity of a PDC particlemade using the subject invention emulsion process.

FIG. 4 shows a SiOC particle according to the invention of approximately1.192 mm in diameter.

FIG. 5 shows a SiOC ceramic particle according to the invention ofapproximately 3.01 mm in diameter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before explaining the disclosed embodiments of the present invention indetail it is to be understood that the invention is not limited in itsapplications to the details of the particular arrangements shown sincethe invention is capable of other embodiments. Also, the terminologyused herein is for the purpose of description and not of limitation.

In the Summary above and in the Detailed Description of PreferredEmbodiments and in the accompanying drawings, reference is made toparticular features (including method steps) of the invention. It is tobe understood that the disclosure of the invention in this specificationincludes all possible combinations of such particular features. Forexample, where a particular feature is disclosed in the context of aparticular aspect or embodiment of the invention, that feature can alsobe used, to the extent possible, in combination with and/or in thecontext of other particular aspects and embodiments of the invention,and in the invention generally.

In this section, some embodiments of the invention will be describedmore fully with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. This invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will convey the scope of the invention to those skilled inthe art. Like numbers refer to like elements throughout, and primenotation is used to indicate similar elements in alternativeembodiments.

The invention includes particles and particles produced from GelatinousPolymer Ceramic Precursors over 3 mm in diameter. The present inventiondescribes SiOC particles/beads/balls that are fully dense particles over3 mm diameter which is were not known prior to this invention. Inaddition, the SiOC particle/bead/ball itself in terms of properties,structure has the potential to add other materials in the polymer stateto make unique one of a kind ceramic particles/balls/beads.

Fully dense particles/beads/balls do not have porosity or the flaws ofporous particles which should allow for better surface characteristicsin terms of roughness and reduction of crack propagation. Larger beads,particles, balls made with porosity have been made but not any that arefully dense in the size ranges of this invention.

In addition, we can use these unique particles/beads/balls to makeunique bulk structures such as those described in U.S. patentapplication Ser. No. 13/775,594 filed Feb. 25, 2013, now U.S. Pat. No.8,961,840 which claims the benefit of priority to U.S. ProvisionalApplication Ser. No. 61/606,007 filed Mar. 2, 2012, both of which areincorporated by reference.

These large fully dense particles have not been made before. “Thepolymer-to-ceramic conversion occurs with gas release, (isotropic)volume shrinkage (20-30%, linear shrinkage) and formation of porosity(micro and macro). This typically leads to large defects, such as cracksor pores, which make the direct conversion of a preceramic part to adense ceramic virtually unachievable, unless its dimension is typicallybelow a few hundred micrometers (as in the case of fibers, coatings, orfoams).” See Colombo et al., Polymer-Derived Ceramics: 40 Years ofResearch and Innovation in Advanced Ceramics, Journal of the AmericanCeramic Society, Vol. 93, No. 7, 2010, pages 1805-1837.

The subject invention covers enhancements to the structure andproperties of gelatinous globules of partially cured pre-ceramic polymerprecursors described in U.S. patent application Ser. No. 13/775,594filed Feb. 25, 2013, which is incorporated by reference.

The parent application, U.S. patent application Ser. No. 13/775,594 (nowU.S. Pat. No. 8,961,840) teaches, “It is important that the droplets notbe 100% cured because they will not be able to form chemical bonds toeach other which means they will not convert to a single continuousceramic body.”

In the parent application, methods were described to produce partiallycured globules or spheres of pre-ceramic polymer precursors. Theseglobules or spheres were then agglomerated to form large bulk 3D shapeswhich were then cured to completion. After full curing the individualspheres are chemically bonded together and when fired will produce asingle continuous ceramic part where the previous individual spheres areindistinguishable.

In the present invention, the term “enhancements” or “enhancementparticles” is used to describe materials added to both the liquid resinand the partially cured globules described herein or added only to thepartially cured globules. The enhancement step entails adding singularor multiple functional materials to the liquid pre-catalyzed polymericceramic precursor resin and also to the surface of the gelatinousglobules while they are sticky due to their partially cured state. Forexample, ceramic or metallic powders of various sizes are added to theliquid precursor resin and can also be pressed or embedded into thesticky surface of the globules which would then be taken to a state offull cure thus incorporating the powders inside the resin and bondingthe powders securely onto the surface of the globules.

Examples of other functional materials that could be added to thesurface of the globules are graphite powder, graphene powder, diamondpowder, carbides, silicides, nitrides, oxides and carbon nanotubes amongothers. The globules can then be re-coated with fresh uncuredpre-ceramic polymer precursors of the same type or a different type.Then the freshly re-wetted globules can then be packed into a mold.Followed by the molded agglomeration of wet, powder coated globulescould be taken to the fully cured state and then pyrolyzed to ceramic.

In addition to or instead of adding powdered materials to the outersurface of the globules, the same materials including nano-scaleversions of these materials could be added to the pre-ceramic polymerprecursors prior to them being formed into the globules or duringglobule formation. Also in addition to or instead of adding powderedmaterials to the outside surfaces of the globules, the surfaces could becoated with pre-ceramic polymer precursors of different families whichgive rise to different ceramics than the ceramic produced by thepre-ceramic polymer precursor that was used to produce the initialglobules. After the globules are coated with a different pre-ceramicpolymer precursor they would be taken to the fully cured state. Thisprocess could be repeated multiple times while alternating thepre-ceramic polymer precursors such that one would end up with an onionlike structure. These multi functionalized globules could beagglomerated together and pyrolyzed to produce bulk ceramic productswith unique properties as described in U.S. patent application Ser. No.13/775,594 filed Feb. 25, 2013, which is incorporated by reference, orthey could be directly pyrolized into functionalized ceramic particles.Advantages of these methods over typical ceramic particle formationinclude lower cost to produce spherical shaped particles (elimination ofor severely reducing mechanical operations to get the sizes needed),less energy to produce the particles, reduced manufacturing time as wellas producing unique sizes, shapes and compositions that cannot beproduced with current particle manufacturing techniques.

FIG. 1 shows a process for making polymer derived ceramic (PDC)particles using an emulsion process. The production of enhanced ceramicparticles via the emulsion process begins by direct injection of aliquid pre-catalyzed polymeric ceramic precursor resin 100, into anemulsifying secondary continuous phase liquid 110 that is immisciblewith the resin. Enhancement particles 160 can the added to the liquidprecursor resin 100 at this stage of the process to incorporatefunctional materials in the precursor resin to produce a unique,functionalized composition. The injection of the precursor resin 100with or without the enhancement particles 160 can be by a spray nozzleor simply poured in, however; the preferred embodiment is to use anultrasonic powered droplet generator 1 which can be a custom builtsystem that takes advantage of Rayleigh instabilities generated in afluid stream by ultrasonic perturbations. Ultrasound powered dropletgenerators typically generate droplets that are about 150 μm in diameterat a rate of 80-100 kHz, but frequencies of up to 1 MHz and dropletsizes ranging from 6 μm to 1 mm in diameter are known. The use of such agenerator allows for the production of liquid droplets 120 with a verytight size distribution and in high volume. Since the two liquids areimmiscible, they won't mix to produce a solution. Instead, the resin 100with or without the enhancement particles 160 will stay in droplet form120 while circulating in the continuous phase liquid 110. To help ensurestability of the emulsion, surfactants can be added to the continuousphase liquid 110 that reduce the interfacial tension between the twoliquids. Examples of surfactants are PEG-12, TWEEN, and Triton-100 amongothers. Examples of the continuous phase liquid 110 are glycerin,propylene glycol, ethylene glycol and fluorinated liquid polymer oilsamong others. Induced currents in the continuous phase liquid 110prevent the resin droplets 120 from coagulating and floating to thesurface.

The continuous phase liquid 110 is then heated in a container 130 bytechniques such as, but not limited to, open flame, electric heatingelements or electromagnetic radiation such as infrared or microwaves. Asthe temperature of the continuous phase liquid 110 rises, the resindroplets 120 are cured to a gel state or a solid in a controlled manner.

In the embodiment shown in FIG. 1, the resin droplets 120 are partiallycured in a heated container 130 to a gel state 140, carried in thecontinuous phase liquid stream 112 to a cured droplet re-coater 150where the desired enhancement particles 160B are introduced into thecontinuous phase liquid stream 114 and allowed to mix with and bind tothe partially cured gelatinous droplets to form liquid coated solidresin droplets 170 with coated particles attached. The amount ofparticles binding to the surface of the gel droplets can be controlledby the amount of particles 160B added to the continuous phase liquidstream and the amount of time the droplets are allowed to spend in theparticle laden liquid stream 114 flow. At this stage the partiallycured, particle encrusted droplets are sent through another heatedcontainer 180 curing cycle, such as, but not limited to open flame,electric heating elements or electromagnetic radiation such as infraredor microwaves to produce cured, coated resin droplets with particlesattached 190. Another embodiment of this invention includes divertingthe partially cured gelatinous droplets 170 with coating particlesattached, to a further recoating step where an additional layer of thesame pre-catalyzed resin or a different pre-catalyzed resin is appliedover the particle laden surface of the partially cured gelatinousdroplets. This has the effect of further anchoring and sealing in theenhancement particles 160B.

In the present invention, the enhancement particles 160 and 160B can bethe same material or can be different materials, depending on thedesired properties and end-use of the ceramic particles or beads.

After recoating, the droplets can then be sent through another curingcycle in a heated chamber, such as, but not limited to open flame,electric heating elements or electromagnetic radiation such as infraredor microwaves to produce cured, coated resin droplets with particlesattached. If it is desired to not recoat the particle encrustedpartially cured droplets then they can be sent to a final curing cyclein a heated chamber 180, as shown in FIG. 1. Once cured, the particleenhanced solid droplets can be immediately pyrolyzed into ceramic beadsor they can be recoated with the original or different catalyzed resinthen packed into a mold then cured in a heated chamber, such as, but notlimited to open flame, electric heating elements or electromagneticradiation such as infrared or microwaves to produce bulk green bodieswhich are then pyrolyzed into bulk ceramic components.

The present application is a Continuation-in-part of U.S. patentapplication Ser. No. 14/598,658 filed Jan. 16, 2014 that describesproducing particles in a hot, non-reactive bath via an emulsion.Emulsions are different from the Sol-gel and Flame pyrolysis used tomake typical ceramic particles. Advantages of emulsion over flamepyrolysis include consistency of particle shape, better control ofparticle size, and the advantage that particles can be shaped andchemically and materially augmented in the polymeric state. Advantagesof Emulsions over typical Sol-gel particle formation include less timefor gelation, simplification of drying process for production of bulkcomponents, stable solutions over time and the advantage that particlescan be shaped and chemically, and materially augmented in the polymericstate before ceramization. Other considerations include the fact thatthe Sol-gel process generally makes particles with porosity. Thisprocess produces particles with very smooth surfaces that are fullydense in the native state at sizes and compositions that cannot be madewith Sol-gel.

FIG. 2 shows a process for making polymer derived ceramic (PDC)particles using a spray process. The production of enhanced ceramicparticles via the spray process begins by direct injection of a liquidpre-catalyzed polymeric ceramic precursor resin 200 into a drop tower210 that is heated by radiant energy 220, such as, heat radiated viaopen flame, electric heaters, or electromagnetic radiation such asinfrared or microwaves. Enhancement particles 250 can the added to theliquid precursor resin 200 at this stage of the process to incorporatefunctional materials in the precursor resin to produce a unique,functionalized composition. The injection of the precursor resin 200with or without the enhancement particles 250 can be by a spray nozzlehowever the preferred embodiment is to use an ultrasonic powered dropletgenerator 2. The use of such a generator allows for the production ofliquid droplets with a very tight size distribution and in high volume.

As the liquid droplets 230 fall through the drop tower 210, surfacetension pulls them into nearly perfect spheres. Air currents areinjected into the drop tower to keep the droplets from hitting the towerwalls and to control the speed of their descent through the tower.Depending on the temperature of the tower and the time spent in thispart of the tower the droplets will be cured anywhere from 0% toapproximately 90% or more.

A coating particle injector 240 containing enhancement particles 250B ispositioned along a vertical side of the tower drop 210; the enhancementparticles 250B are blown into the drop tower 210. The enhancementparticles 250B are of a size such that when taking into account theirdensity, that they can be made to flow around inside the drop tower 210in a dust cloud state. This dust cloud of enhancement particles 255 theninteracts with the falling partially cured resin droplets. In the eventthat the particles are cured to a gelatinous state by the time theyencounter the dust cloud the particles can only adhere to the outersurface of the sticky droplets.

If the air currents and temperatures are set such that the liquid resindroplets 230 are still in a liquid state, the enhancement particles 250Bwill attach to and migrate into the body of the droplets in affectimpregnating and filling the liquid droplets with particles. The amountof particles 250B inside each droplet 260 is controlled by the densityof the dust cloud and the temperature of the drop tower 210.

As the coated or impregnated and filled droplets 260 continue down thetower they finish curing to a solid state. The cured particles 270 arethen collected at the bottom of the drop tower 210.

The amount of enhancement particles 250B that bind to the outer surfaceof the liquid resin droplets 260 is controlled by the density of thedust cloud and the temperature of the drop tower. Once cured, theparticle enhanced solid droplets can be immediately pyrolyzed intoceramic beads or they can be recoated with the original or differentcatalyzed resin then packed into a mold then cured in a similar curecycle as above into bulk green bodies which are then pyrolyzed into bulkceramic components.

A determination as to whether the liquid resin droplets 230 are filledor coated can be made judiciously, depending on the vertical position ofthe coated particle injector 240 on the side of the drop tower 210, ifpositioned near the top where liquid resin 200 is injected into the droptower, the enhancement particles 250 can be incorporated inside theresin droplets and if positioned midway or lower on the vertical side ofthe drop tower when the liquid resin droplets 230 are partially cured,the enhancement particles 250 are deposited on the outside of thedroplets.

Another method of producing very small nano-scale particles would be totake the green body produced by the bulk technique and thencryogenically freezing this polymer mass. Then, through mechanicaltechniques such as cyro-milling or other mechanical techniques, verysmall (less than one micron particles) could be produced by pulverizingthe polymer in a frozen state. Once the frozen polymer is milled to thedesired size it would then be pyrolyzed to ceramic. It is much moreenergy efficient than typical ceramic particle manufacturing where themilling process is performed on hard ceramic materials which producesextreme wear on the milling equipment.

When the functionalized globules are agglomerated together, theresultant bulk ceramics produced can be unique in that they wouldpossess a multi-material structure virtually unobtainable by any othermeans. Such ceramics could be tailored to have higher strength,toughness, hardness or temperature resistance than ceramics with simplerstructure.

Polymer Derived Ceramics are typically additive-free ceramic materialspossessing excellent oxidation and creep resistance up to exceptionallyhigh temperatures. The most known classes of PDCs are in the binarysystems Si₃N₄, SiN, BN, and AlN, ternary systems SiCN, SiOC, and BCN aswell as the quaternary systems of SiCNO, SiBCN, SiBCO, SiAlCN, andSiAlCO. See Colombo et al., Polymer-Derived Ceramics: 40 Years ofResearch and Innovation in Advanced Ceramics, Journal of the AmericanCeramic Society, Vol. 93, No. 7, 2010, pages 1805-1837. Any mention ofSiOC in this memorandum will also mean the usage of these other types ofpolymer derived ceramics and their composite systems.

Table 1 shows Polymer Derived Ceramic systems with particle range size,applications and both density ranges.

Application Density Specific PDC Particle Range Proppants Ball BearingsRange Density System Full Range Narrow Range Preferred Preferred (g/cc)(g/cc) SiOC 0.1-100 mm 0.2-10 mm 0.1-1.0 mm 0.5-10 mm 1.7-2.8 2.1-2.2SiCN 0.1-100 mm 0.2-10 mm 0.1-1.0 mm 0.5-10 mm 1.85-2.3  2.1-2.3Si—Ti—C—O 0.1-100 mm 0.2-10 mm 0.1-1.0 mm 0.5-10 mm 1.9-2.6 2.35Si—Al—C—O 0.1-100 mm 0.2-10 mm 0.1-1.0 mm 0.5-10 mm 2.8-3.4 3.0-3.1Si—B—C—N 0.1-100 mm 0.2-10 mm 0.1-1.0 mm 0.5-10 mm 1.80-2.3  2.1-2.3 BN0.1-100 mm 0.2-10 mm 0.1-1.0 mm 0.5-10 mm 1.8-2.1 1.95 Si—Al—O—N 0.1-100mm 0.2-10 mm 0.1-1.0 mm 0.5-10 mm 2.3-3.0 2.6 SiC 0.1-100 mm 0.2-10 mm0.1-1.0 mm 0.5-10 mm 3.0-3.3 3.05Applications of the PDCs

Depending on the functionalization, these ceramic particles or beads canbe used to make inexpensive anti-bacterial water filters or if theparticles are functionalized with catalytic materials, they could beused to produce low cost, high temperature chemical reactors orcatalytic converters.

Proppants

Other examples where the individual particles can be used includeproppants for fracking oil and gas wells. In house testing ofcompression strength of the as fabricated

SiOC beads that were in the target diameter range of approximately 354to approximately 420 microns gave an average per bead load at failure ofapproximately 36 pounds. Applying Hertzian contact stress analysis tothis load case gives a compression strength in excess of approximately685,000 psi (approximately 4.73 Gpa) which exceeds that of alumina atapproximately 453,000 psi (approximately 3.0 Gpa), Si₃N₄ atapproximately 508,000 psi and silicon carbide at approximately 667,000psi (approximately 4.6 Gpa). Beads of this strength would be expected tofar exceed the industry benchmark “crush strength” of approximately20,000 psi which represents beads made of high alumina. This dataindicates that the SiOC particles should exceed a “crush strength” ofapproximately 30,000psi.

Hybrid Bearings

A hybrid ball or roller bearing is defined as a non-metallic ball orroller in contact with a metal race. The non-metallic balls or rollersare typically silicon nitride, aluminum oxide, or other ceramicmaterials. Hybrid bearings provide the following benefits compared totraditional all-metallic ball or roller bearings: increased speeds,improved life, lower wear resistance, run at cooler temperatures, lowerinitial and life cycle costs, increased bearing life, non-magnetic,lightweight, reduces corrosion, improved electrical insulation (reduceselectrical arcing), allows design to tighter tolerances, enablessimplified lubrication systems, provides high modulus of elasticity, lowcoefficient of friction (reduced heat generation), and improves assemblyrigidity.

SiOC ball blanks can be finished to grade 3, 5, 10 and 24 precision indiameter sizes ranging up to 4 mm. Many bearing applications fall intothe small ball (ie. <approximately ⅛″ or approximately 3 mm) diameterrange. Two examples include dental drills/medical hand pieces (1 mm-1/16″ diameter bearing balls) and hard disk drive spindles (1 mm- 7/64″diameter bearing balls).

SiOC spheres possess ideal bearing ball properties. They are fully denseand will reduce wear and heat generation. The hardness of SiOCsignificantly extends bearing wear characteristics and the modulus ofelasticity is greater than steel, which improves bearing rigidity.Minimal lubrication is required using SiOC bearings and lower torque canbe achieved due to low friction characteristics. SiOC is virtually inertand improved corrosion resistance compared to steel. The fully densemicrostructure of SiOC allows extremely fine surface finishes ofapproximately 0.1 to approximately 0.2 Ra. Higher speeds can be achieveddue to SiOC's low density and lightweight properties.

Adhesive wear is also reduced. Special properties include electricalinsulation and it is non-magnetic. Besides SiOC, the technologydescribed can make composites of SiOC as well as other systems made fromPDC resins. Silicon nitride is the current ceramic ball bearing leader.

The PDC components of this invention have lower density, lowermanufacturing costs, and higher compressive strength than the siliconnitride market leader as well as other standard ceramics.

A typical ball bearing ceramic process for silicon nitride ball bearingsinvolves the milling of high purity raw materials mixed with binders.These powders are then spray dried creating a feedstock with excellentflowability and a range of particle sizes to ensure optical packing ofmolds. Spray dried powders are then carefully pressed under uniformpressure so that there are no density variations across the bearings andthen prefired to remover binders. The prefired forms are then heatedunder pressure using a process called hot isostatic pressing or HlPing,using carefully predetermined heating schedules to optimizemicrostructural development for properties such as hardness, toughness,and rolling contact fatigue. The fired ceramic bearings are then lappedto final dimensions/geometry producing an excellent surface finish.“Silicon Nitride Ceramic Ball Bearings—Properties, Advantages andApplications.”AZOM.com. N.P., 11 Jun. 2013. Web. 13 Sep. 2014.

FIG. 3 is photograph of a small ball bearing 300 made with the emulsionprocess disclosed in the present invention. The size is approximately0.412 mm in diameter with a roundness of less than 0.018 mm. Using anOptical comparator (Smart Scope, ZIP Lite 250), a particle prepared bythe present invention is affixed to a stage, a light source shines onit, and the resulting shadow image of the particle is magnified withlenses and bounced by mirrors, to be projected on the back of a screenfor magnified viewing. The light source is Light Emitting Diodes (LEDs)wherein the LEDs are reflected back from the polished surface of amagnified particle 300. The Optical comparator, distributed by OpticalGaging Products, Inc., shows a smooth, glossy, mirror-like surfacefinish which was an incredible outcome without mechanical shaping orpolishing. In addition, the particles are substantially, perfectlyspherical and suitable for use as ball bearings and are much cheaperthan the current process for preparing silicon nitride ball bearings interms of thermal energy, manufacturing steps, and mechanical shapingtime and expense.

FIG. 4 is a high resolution image of a SiOC ceramic particle 400prepared by the emulsion process of the present invention showing acompletely spherical particle measuring approximately 1.192 mm indiameter.

FIG. 5 is a fully dense, spherical SiOC ceramic particle 500 preparedaccording to the invention measuring approximately 3.01 mm in diameter.

Dispersion and Grinding Media

Ceramic grinding and dispersion media can be used for particle sizereduction and typically produced from hard, wear-resistant ceramicmaterials such as zircon, alumina, and various alloys of zirconia.Grinding media can also be produced from the following materials: sand,plastics, glass, steel and tungsten carbide. Typical geometries forceramic media included spheres, banded spheres, and cylinders. Sphericalgeometries are very common and are also known as beads.

Grinding media and dispersion media can be used in the manufacturing ofpaints, automotive coatings and inks, pigments, ores, minerals, a broadrange of ceramic powders for electronic applications (ie. manufacturingof dielectrics), food processing, agrochemicals, and pharmaceuticals toname a few examples. Ceramic grinding media is commonly used in variousequipment such as high energy mills, horizontal & vertical mills,vibratory mills, balls mills, and basket mills.

Hard ceramic materials exhibit high crush strength and wear resistance.Alloys of zirconia possess high density and crush strength as well asrelative inertness to most acidic and alkali fluids. It is frequentlyused in aqueous based processes, especially in high speed agitationmills. The characteristically higher mass of zirconia provides thegreater power (kinetic energy) needed by automotive coating and inkformulations, including the processing of highly viscous materials.

The properties of SiOC can be tailored to meet the requirements of mostgrinding media applications. Zirconia grinding media is ideal forsurviving harsh conditions. Standard sizes for ceramic grinding mediabeads ranges from approximately 0.03 to approximately 2.4 mm indiameter.

The ideal ceramic grinding and dispersion media exhibits the highestwear resistance at the lowest cost per lbs or Kg with a tailored densityfor the application. Properties include:

-   -   High density provides a larger impact force which results in        superior grinding efficiency.    -   High surface finish, roundness, sphericity, and a narrow size        distribution produces higher productivity grinding and        dispersion.    -   Made from high purity materials, which results in higher wear        resistance and minimal contamination from media wear.    -   Inert and corrosion resistant        Ceramic Media for Surface Treatment and Cleaning

Ceramic media can be used for surface processing of a broad range ofsubstrate materials—from hard steel to light alloys, polymers, andceramics. Zirconium silicate for example, can be used for surfacecleaning rubber and plastic molds, castings, boiler and heat exchangerparts, shot peening of various parts, cleaning nuclear reactorcomponents, deburring a broad range of metal parts, and surfacepreparation of metal parts.

Ceramic beads perform efficiently in dry or wet pressure blastingsystems and in multi-turbine blasting equipment. Ceramic media reducesdust emissions, maintains their round shape, smooth surface finish, andhigh strength. Ceramic media is chemically inert, corrosion resistant,and does not contaminate the substrate that is being processed. Thisinvention will provide the means for alternate ceramic and/or ceramiccomposites.

Catalyst Cracking

Ceramic beads made from aluminium oxide (Al₂O₃) can be used in catalystsfor petroleum cracking. This invention will supply alternatives whichmay improve catalytic performance.

The term “approximately” can be +/−10% of the amount referenced.Additionally, preferred amounts and ranges can include the amounts andranges referenced without the prefix of being approximately.

While the invention has been described, disclosed, illustrated and shownin various terms of certain embodiments or modifications which it haspresumed in practice, the scope of the invention is not intended to be,nor should it be deemed to be, limited thereby and such othermodifications or embodiments as may be suggested by the teachings hereinare particularly reserved especially as they fall within the breadth andscope of the claims here appended.

We claim:
 1. A polymer derived ceramic (PDC) particle, wherein theparticle material is derived from at least one of a binary PDC system, aternary PDC system or a quaternary PDC system formed in a sprayingprocess for producing bulk ceramic components from an agglomeration ofpartially cured polymer ceramic precursor resin material, the final PDCparticle consisting of: a plurality of liquid pre-catalyzed polymericceramic precursor resin droplets that are injected into a drop towerheated by radiant energy and as the liquid resin droplets fall from thetop portion of a drop tower, a plurality of non-porous partially-curedglobules of polymer ceramic precursor material is formed, and aplurality of powder particles that are functional material fillers issprayed onto the structure of the partially-cured globules of polymerceramic precursor material that is subsequently fully cured, chemicallybonded together, then fired to produce a uniform, fully-dense, solid,single, continuous ceramic part having a particle size of approximately2.1 mm to approximately 300 mm in diameter.
 2. The polymer derivedceramic (PDC) particle of claim 1, wherein the binary PDC system is atleast one of boron nitride (BN) or silicon carbide (SiC).
 3. The polymerderived ceramic (PDC) particle of claim 1, wherein the ternary PDCsystem is at least one of SiCN or SiOC.
 4. The polymer derived ceramic(PDC) particle of claim 1, wherein the quaternary PDC system is at leastone of Si—Ti—C—O, Si—Al—C—O, Si—B—C—N, or Si—Al—O—N.
 5. The polymerderived ceramic (PDC) particle of claim 1, wherein the plurality ofpowder particles in the structure of the partially-cured globules ofpolymer ceramic precursor material includes at least one of a firstcoating of a first functional material coated on the surface of thepartially-cured globules of precursor material or a second coating of asecond functional material coated on the surface of a fully curedpolymer ceramic precursor material having the first coating of the firstfunctional material, thereby forming a functionally enhancedmultilayered ceramic particle.
 6. The polymer derived ceramic (PDC)particle of claim 5, wherein the functional material selected is from atleast one of a metallic powder, a ceramic powder, graphite powder,graphene powder, diamond powder, carbide powder, silicide powder,nitride powder, oxide powder, carbon nanotubes and mixtures thereof. 7.The polymer derived ceramic (PDC) particle of claim 1, the particlehaving a density range of approximately 1.7 to 3.4 g/cc.
 8. The polymerderived ceramic (PDC) particle of claim 1, wherein the particle is fullycured, then pyrolyzed to form a ceramic proppant.
 9. The polymer derivedceramic (PDC) particle of claim 1, wherein a ceramic ball bearing isformed when the particle is fully cured, then pyrolyzed.
 10. Anano-sized polymer derived ceramic (PDC) particle, wherein the particlematerial is derived from at least one of a binary PDC system, a ternaryPDC system or a quaternary PDC system formed in an emulsion process forproducing bulk ceramic components from partially cured polymer ceramicprecursor resin droplets comprising the steps of: a) providing a liquidpre-catalyzed polymeric ceramic precursor resin; b) introducing theprecursor resin to a continuous phase liquid emulsion; c) exposing thecontinuous phase liquid emulsion containing the precursor resin to anenergy source; d) forming a plurality of partially cured polymer resinglobules; e) shaping the partially-cured polymer resin globules into agreen body; f) cryogenically freezing the green body; g) pulverizing thefrozen green body in a frozen state; h) milling the frozen green bodyinto particles less than one micron in diameter; i) pyrolyzing themilled frozen green body particles to form a plurality of fully dense,non-porous nano-scale ceramic particles with a smooth surface.
 11. Thepolymer derived ceramic (PDC) particle of claim 10, wherein the binaryPDC system is at least one of boron nitride (BN) or silicon carbide(SiC).
 12. The polymer derived ceramic (PDC) particle of claim 10,wherein the ternary PDC system is at least one of SiCN or SiOC.
 13. Thepolymer derived ceramic (PDC) particle of claim 10, wherein thequaternary PDC system is at least one of Si—Ti—C—O, Si—B—C—N, orSi—Al—O—N.
 14. A method of making a fully-dense, spherical polymerderived ceramic (PDC) particle, wherein the particle material is derivedfrom at least one of a binary PDC system, a ternary PDC system or aquaternary PDC system formed in an emulsion process for producing bulkceramic components from partially cured polymer ceramic precursor resindroplets comprising the steps of: a) providing a liquid pre-catalyzedpolymeric ceramic precursor resin b) introducing the precursor resin toa continuous phase liquid emulsion, c) exposing the continuous phaseliquid emulsion containing the precursor resin to an energy source, d)forming a plurality of partially cured polymer resin globules; e) mixinga plurality of powders with the continuous phase liquid emulsioncontaining the partially cured polymer resin globules; f) coating thepartially cured polymer resin globules with powder particles, g)separating the coated partially cured polymer from the continuous phaseliquid emulsion; and h) pyrolyzing the coated partially cured polymer toproduce a plurality of fully-dense, solid, non-porous polymer derivedceramic (PDC) particles having a particle size of approximately 2.1 mmto approximately 300 mm in diameter.
 15. The method of claim 14, whereinthe binary PDC system is at least one of boron nitride (BN) or siliconcarbide (SiC).
 16. The method of claim 14, wherein the ternary PDCsystem is at least one of SiCN or SiOC.
 17. The method of claim 14,wherein the quaternary PDC system is at least one of Si—Ti—C—O,Si—Al—C—O, Si—B—C—N, or Si—Al—O—N.
 18. The method of claim 14, whereinthe liquid pre-catalyzed polymeric ceramic precursor resin of step a) ismixed with a plurality of powder particles before introducing theprecursor resin to the continuous phase liquid emulsion of step b). 19.The method of claim 14, wherein the process steps a) through g) arerepeated multiple times to create multiple layers of functionalparticles on the coated partially cured polymer resin globule forming anonion-like, layered, multi-functional composite that is fully cured andthen pyrolyzed to produce a multilayered polymer derived ceramic (PDC)particle.
 20. The method of claim 14, wherein the plurality of particlesis a functional material selected from at least one of a metallicpowder, a ceramic powder, graphite powder, graphene powder, diamondpowder, carbide powder, silicide powder, nitride powder, oxide powder,carbon nanotubes and mixtures thereof.